Apparatus for cutting helical propellers



C. H. GRANT. APPARATUS FOR CUTTING HELICAL PROPELLERS.

APPLICATION FILED NOV-22, 1919.

1,333,912. Patented Mar. 16, 1920.

2 SHEETS-SHEET l.

C. H. GRANT.

APPARATUS FOR CUTTING HELICAL PROPELLERS.

APPLICAHON FILED NOV. 22, 1919.

( Patented Mai. 16, 1920.

2 SHEETS-SHEET 2- ['1' III-,

CHARLES HAMPSOTI GRANT, OF NEVT YOR K, N. Y.

APPARATUS FOR. CUTTING HELICAL PROPELLERS.

Specification of Letters Patent.

Patented Mar. 16, 1920.

Application filed November 22, 1919. Serial No. 340,022.

To all whom it may concern Be it known that I, CHARLES HAMPsoN GRANT, acitizenof the United States, residing in the city, county, and State ofNew York, have invented certain new and useful Improvements in Apparatusfor Cutting Helical Propellers, of which the following is aspecification.

This invention relates to improved means for cutting helical bladedpropellers of the type used in airplanes;

The principal objects of the invention are to simplify the operationsand to reduce the cost of manufacturing propellers by providingapparatus for mechanically cutting helical blades on rough propellerblanks.

The invention consists in certain features of construction, arrangement,and combination of parts, hereinafter described and particularly pointedout in the claims.

the accompanying drawings, il1ustrating my invention,

Figure 1, is a top view of 'a jig used for holding the propeller blankin cutting the back or convex face of the blade;

7 F ig. 2, is a side view thereof;

Fig. 3, is a fragmentary perspective view of a shaper showing the knivesemployed in forming the back of the blades;

Fig. 4: is aside view of one of the knives used in cutting the front ofthe blade;

Fig. 5, is a -t0p view of the jig used in forming the front or concaveface of the blade;

Fig. 6, is a side view of the same;

Fig. 7, is a vertical section on the line 7-7 I of Fig. 6; and

Fig. 8, is a perspective view 'of the propeller blank. I

- The apparatus employed in carrying out my invention consists,generally, of an ordinary shaper provided with removable cutting knives,a jig for holding the blank in cutting the back of the blades, and asecond jig for holding the blank in cutting the *front of the blades.

In the manufacture of the propeller, I- take a blank A having thegeneral outline of a double-bladed propeller, such as is the bladesafter which the blank is turned endwise in the jig and the back of theother blade is out. After the back of the blades have been formed, theblank is removed from said and placed in the second jig with the back ofthe'blades downward, and then the front faces of the two blades aresuccessively cut.

The rotary shaper employed in cutting the blades may be of any ordinaryor approved construction. As illustrated in the drawings it consists ofa revolving vertical shaft 1 projecting through an opening in theworlctable 2 and provided with a fixed collar 3 and a removable collar 4between which the cutting knives 5 are held. The collars are formed withgrooves into which the knives fit and a nut 7 is provided for clampingthe collars together so as to tightly hold the knives in position.

It is essential that the knives be formed with parabolic cutting edges.The knives shown in Fig. 3, are provided with con cave parabolic-shapedcutting edges 6' and are used in forming the back or convex face of theblades, while the knives 5", 'one of which is shown in Fig. 4, areformed with convex parabolic shaped cutting edges 6' and are used incutting the front or concave face of the blades;

My improvement relates particularly to the jigs in which the propellerblank is held while the faces of the blades are being cut by theparabolic-shaped knives revolving at highspeed. Referring now to Figs. 1and 2, the jig used in making thefirst cut consists of a base 8, a plate9 adjustably mounted on the base, and an inclined blocklO carried on theplate. The block 10 preferably has its lower end hinged at 11 to theplate 9 and has its upper end supported in graduated arms 12 so that theangle of inclination of the block may be adjusted to permit of varyingthe pitch of the blades. .A cavity13, substantially similar in outlineand depth to the blank A, is formed in the inclined face of the block toreceive and hold said blank. A portion of one side of the block 10 iscut away as indicated at 14 so as to expose an end of the blank and toallow the shaper knives to come into cuttin contact therewith. It willbe m'lde'rstoo" that incutting in arms 12.

the blades the position of the rotary sha per is stationary and that thejig is moved on the surface of the work table thereof.

The front ed e of the is formed with a cam-shaped recess 15 of suchconfiguration that when the jig is pressed against the collar 3 of theshaper, the lower or hub portion of the exposed end of the blank willcontact with the heel or lower portion of the cutting edges 6 of theknives 5, and

that as the jig is moved endwise, in the direction of the arrow in Fig.1, the line of cutting contact will gradually travel from the heeltoward the point of the knives, thus producing the desired helical shapeof the back of the'blade.

An arm 16, pivoted at 17, is provided to hold one end of the blankfirmly in place in the jig while the other end is being out and toprevent the blank from chattering during the cutting operation. The armis locked in its holding positlon by means of .9, and an. inclined block10 having its lower end hinged at 11 to the plate 9 and having its upperend adjustablysupported The block 10 of this jig is inclined in theopposite direction of the block 10 of the jig heretofore described. Thejig is provided with a cavity 13 for receiving the blank, the bottom ofwhich cavity is shaped to correspond with the back of the blades, asseen in Fig. 7. A portion of the block 10 18 cut away as at 14: to allowthe knives 5 to come into contact with the end of the blank, which is tobe out.

In cutting the front face of the blades the knives 5 of the shaper arereplaced by the knives 5, one of which is shown in Fig. 41-, whichknives have convex parabolic cutting edges 6. The cam-shaped recess 15'of the jig is so designed that when the jig is pressed against thecollar 3 and is moved in the direction of the arrow in Fig. 5, the lineof cuttingcontact of the knives 5 will travel from the point to the heeland will thereb cut the front face of the blade in the desired helicalshape. nn arm 16 pivoted at 17 and adapted to be locked by the lever 18is provided to firmly hold one end of the blank in the jig while theother end is being out.

When the front face of one "blade has bee-n of the shaper 2. Inapparatus for cutting helical propeller blades, the combination with arotary shaper,. of a jig for holding a propeller blank with an endportion exposed and ar ranged that when the jig is moved in operativerelation to the shaper the knives of the latter will out the surface ofthe exposed end portion of the blank to form one face of the blade.

3. In apparatus for cutting helical propeller blades, thecombinationwith a rotary shaper having parabolic shaped knives, of a jigfor holdinga propeller blank in an inclined position with one bladeexposed, said jig being constructed that when 'it is moved in operativerelation to the shaper the knives will engage the exposed blade at itshub and will cut the blade from the hub outward.

4:. In apparatus for cutting helical pro peller blades, the combinationwith a rotary shaper having a collar and provided with knives formedwith parabolic shapedcutting edges, of a jig for holding a propellerblank in an inclined position with one blade exposed to the action ofthe knives, said jig having a recessed portion serving as a guide, whenthe jig is moved with its recessed portion pressing against the collarof the shaper, to cause the knives to out the exposed face of the bladein'helical shape.

5. In apparatus for cutting helical propeller blades, a jig comprisingan inclined supporting member provided with a seat for a propeller blankand having a portion cutaway to expose an end of the blank, and a basemember formed with an irregular shaped recess disposed substantially inline with the cut-away portion of the supporting member. 7

6. In apparatus for cutting helical pr0- .peller blades, a jigcomprising an inclined supporting member provided with a seat for apropeller blank and having a portion cut-away to expose an end of theblank, means mounted on said memberfor firmly holding. the blank inritsseat, and a base memberformed with an irregular shaped recess disposedsubstantiallyin line with the cut-away, portion of the supportingmember. 7 I

'7. In apparatus for cutting helical propeller blades, a jig comprisingan adjustably inclined supporting block formed with a seat I forreceiving a propeller blank and having a portion of the block cut-awayto expose one end of the blank, a member pivoted on the block andengaging the other end of the blank to firmly hold it in its seat, and abase member formed with an irregular shaped recess disposedsubstantially in line with the 10 cut-away portion of the block.

8. In apparatus for cutting helical propeller blades, a jig comprising abase having an irregular shaped recess, a plate ad]ustably mounted onthe base, and an inclined 15

